It is becoming widely accepted that a complicated interplay exists between the gut microbiome and human host metabolism. Gut bacteria aid in the digestion and metabolism of certain foods we eat, providing us not only with nutrients we can use, but also sometimes with potentially harmful metabolites. Trimethylamine N-oxide (TMAO), for example, is produced from the microbial metabolism of dietary choline and carnitine and might increase the risk for cardiovascular disease. Dysbiosis, or an imbalance of the microbiota, has been linked to numerous metabolic conditions such as obesity and cardiovascular disease (CVD), although specific mechanisms remain largely unknown. Now, Fu et al. examine the partnership between the gut microbiome and blood lipids, which are strong risk determinants of heart disease.

The authors studied 893 participants in the LifeLines Cohort in the Netherlands to examine the relationship between the gut microbiome and blood lipid concentrations. Fecal samples were analyzed, bacterial DNA sequenced, and microbial diversity (that is, the variability of bacterial composition) quantified. Greater microbial diversity was associated with lower body mass index (BMI), lower blood triglyceride levels, and higher HDL cholesterol; among specific bacteria that correlated with these parameters were several known to participate in bile-acid and short-chain fatty acid metabolism. Investigators also reported an independent microbial contribution to the variation in blood triglycerides and HDL beyond that explained by genetics and traditional risk factors (age, gender, BMI).

Although further studies are needed to prove causality, these data support a role for the gut microbiome in the regulation of blood lipids and potentially heart-disease risk. If true, therapies to modify the gut microbiome may be a viable option for correcting lipid abnormalities. If the idea of fecal transplants is hard to stomach, dietary changes already known to correct blood lipids might be a more palatable option. But bug or no bug, CVD patients and healthy individuals exert control over their diets.